1. Field of the Invention
This invention relates to an outboard motor steering control system, particularly to an outboard motor steering control system for steering multiple outboard motors.
2. Description of the Related Art
When two or more outboard motors are mounted on the stem of a hull (boat) in what is known as a multiple outboard motor installation, the outboard motors are usually connected by links called tie bars for enabling mechanically interconnected steering of the outboard motors, as disclosed in Japanese Laid-Open Patent Application No. Hei 8 (1996)-276896, for example.
In the case of multiple outboard motor installation, the straight course-holding performance or turning performance of boat can be improved by giving the outboard motors different steering angles in response to the cruising conditions so as to regulate their relative angles. To be more specific, straight course-holding performance can be improved by establishing the relative angles so that extensions of the propeller axes of rotation intersect forward of the outboard motors, thereby minimizing lateral deflection of the boat. Turning performance can be improved by making the extensions of the propeller axes of rotation intersect rearward of the outboard motors.
When multiple outboard motors are mechanically interconnected by tie bars as in the prior art, the relative angles between the outboard motors are solely or uniquely determined. This makes it impossible to regulate the relative angles between the outboard motors in response to the cruising conditions, so that improvement of both straight course-holding performance and turning performance cannot be achieved.